In recent years, an area of intensive research has been in the conservation of battery life of a mobile device. As a greater number of applications are becoming available that require near constant network access and require power on a near constant basis, the previous methods of conserving power on a mobile device are not compatible with today's trend of increased data and power usage.
One of the issues is a frequent use of network assets as the mobile devices disconnect from the network and then attempt to reconnect after a short amount of time. The connection/reconnection attempts consume signaling bandwidth, and when a large number of devices are attempting to access the network, a large amount of the signaling bandwidth is consumed.
In long term evolution (LTE) networks, discontinous reception (DRX) is a power saving method executed by a mobile device during communication between the mobile device and a cellular communication network to which the mobile device is connected. DRX is a setting in the mobile device that is set by an entity in the cellular communication network (e.g., an eNodeB) based on a message to a mobile device (i.e., the User equipment (UE) in a mobile network context). The DRX message from the eNodeB instructs the UE to remain in one of two states: connected or inactive. Said differently, when the UE receives a DRX “connected” message the UE remains active (i.e., stays connected—receiving data from and/or transmitting data to the network), but when the UE receives the “inactive” DRX message, the UE sleeps (i.e., goes into or remains in an inactive state—remains idle and does not receive or transmit data to the network). The UE follows a protocol defined by the network to switch between sleep and active modes. The longer the sleeping period and shorter the active periods, the greater the power savings.
However, there is a trade off between data throughput and power saving. From a power saving point of view, a UE needs to more frequently enter into the sleep mode to save power. But to send or receive data, the UE then has to transition back to the active state. Transition to an active state includes signaling the network. Depending on the traffic patterns, the UE may frequently transition between sleep mode and active mode, which may result in high volume of network signalling and/or data throughput jitter. Jitter may be defined as arrival time variations of voice-over-IP (VoIP) packets due to network congestion, timing drift, and/or route changes. From the throughput point of view, the UE should always be active in order to achieve the best data throughput results. It is very difficult to achieve a balance between power savings and throughput.
Typically, an eNodeB of a cellular communication network provides DRX setting instructions to an UE. Based on the DRX setting instructions, the UE sets its DRX setting. For example, the eNodeB will set one DRX setting for VoIP, while data communication will have another DRX setting. Currently, the eNodeB has complete control of the DRX settings for a UE, and the UE has no input into the DRX setting. The DRX setting instructions sent by an eNodeB may not conform to the current use of the UE.
However, in a latest standard release, 3GPP standard, Release 11, a UE can send a signal to an eNodeB of cellular communicaiton network that influences the network configuration. The signal sent by the UE is a Power Preference Indicator (PPI), which is a single bit value (i.e., 0 or 1) indication defined by 3GPP standard, Release 11.
It has been suggested to use the PPI signal to select between a low latency DRX profile (PPI=0) (e.g., remains active for longer periods but sleeps less) and a low power DRX profile (PPI=1) (e.g., sleeps more often or for longer periods but is less active). However, this suggestion allows only two possible profiles since the PPI is a single bit definition state indicator. Due to different types of data traffic and UE data usage scenarios, there is a need to have more flexible ways to specify and control more than two DRX profiles so a better balance between power and throughput may be achieved.